<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK IT ]
// +----------------------------------------------------------------------
// | Copyright (c) 2009 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: liu21st <liu21st@gmail.com>
// +----------------------------------------------------------------------

/**
 * Crypt 加密实现类
 * @category   ORG
 * @package  ORG
 * @subpackage  Crypt
 * @author    liu21st <liu21st@gmail.com>
 */
class Crypt {

	/**
	 * 加密字符串
	 * @access static
	 * @param string $str 字符串
	 * @param string $key 加密key
	 * @return string
	 */
	function encrypt($str,$key,$toBase64=false){
		$r = md5($key);
		$c=0;
		$v = "";
		$len = strlen($str);
		$l = strlen($r);
		for ($i=0;$i<$len;$i++){
			if ($c== $l) $c=0;
			$v.= substr($r,$c,1) .
			(substr($str,$i,1) ^ substr($r,$c,1));
			$c++;
		}
		if($toBase64) {
			return base64_encode(self::ed($v,$key));
		}else {
			return self::ed($v,$key);
		}

	}

	/**
	 * 解密字符串
	 * @access static
	 * @param string $str 字符串
	 * @param string $key 加密key
	 * @return string
	 */
	function decrypt($str,$key,$toBase64=false) {
		if($toBase64) {
			$str = self::ed(base64_decode($str),$key);
		}else {
			$str = self::ed($str,$key);
		}
		$v = "";
		$len = strlen($str);
		for ($i=0;$i<$len;$i++){
			$md5 = substr($str,$i,1);
			$i++;
			$v.= (substr($str,$i,1) ^ $md5);
		}
		return $v;
	}


	function ed($str,$key) {
		$r = md5($key);
		$c=0;
		$v = "";
		$len = strlen($str);
		$l = strlen($r);
		for ($i=0;$i<$len;$i++) {
			if ($c==$l) $c=0;
			$v.= substr($str,$i,1) ^ substr($r,$c,1);
			$c++;
		}
		return $v;
	}
}